Genius Hacker Kid - Developed Worm/Virus, trusts this leader dude who might be a priest (pretty sure it's something similar). Might have a sister that's being leveraged against him near the end of the story, or hes mislead into thinking that whats hes doing is for her benefit.
Bank Net Security Gal - Hacker who works for one of the first banks hit by the virus, catches a glimpse of the worm robbing her bank and proceeds to try and prevent it and fails. Her attempts draw the attention of bad guys and she becomes targeted by them in the real world as they try to kill her. She learns of one of her friends/acquaintances, who worked at another bank that was robbed, and is dead probably because he also saw more than he should have. She escapes her apartment being blown up and while running for her life she stops at a convenience store to buy stuff with a gift card she stole from inside a box of cereal or some such thing because she cant use her money from her real identity which is stored in an RFID chip type of device in her body somewhere.
Leader dude - Dies at the end either by the security chick or some other policeman type character. Lying to the young genius kid about his evil plans. I'm pretty positive he's a priest or bishop or some such thing; I distinctly remember religious overtones about the leader guy and his organization.
Specifically stated in the book is that the code is only being tested when the security chick sees it. I'm also pretty sure that the bad guys let the world know they were going to rob the bank and that there wasn't anything they could do about it.
Possible existence of hover bike/skates/board, or it might just be a regular version thereof. The security chick uses one to escape her attackers after her apartment is blown up.
Somehow, security chick tracks down the boy/virus to a remote compound. She either beats the virus, or convinces the boy to stop, or he realizes he's being used and refuses to use the virus further.
The Virus/Worm is nigh untraceable/unbeatable due to its architecture. Upon activation it attacks a bank account and steals all the money inside. Before it proceeds to the next account it makes two copies of itself that fight each other. The winner, and obviously the stronger, eats the loser and the parent and goes to the next account with all the amassed loot and an entirely different footprint than its parent which hides its tracks.